The precise control of electromechanical actuators is important in numerous applications, such as typical aircraft control surface applications. In such applications, as the bandwidth of a system approaches that of the load natural frequency, instability can result. The dynamic interaction of the motor and a compliant load can lead to undesirable phase lag which results in degraded closed loop system stability. The control signal is sensitive to noise generated by the sensor being utilized, such as a tachometer for sensing motor rate. Typically, only a single position sensor is utilized and such a sensor generally is not accurate over the whole system operating bandwidth. Also, compensation to stabilize the motor control loop in the region of the motor/load natural frequency can be complicated and expensive.
Complementary filters can be utilized to combine or reconstruct a signal from an assortment of dissimilar sensor measurement signals. For example, in the flight control industry, a barometric altitude sensor signal and an acceleration sensor signal are combined to obtain an estimate of the verticle speed of a vehicle. The benefit is a more accurate signal over the system operational frequency range than the signals of any of the individual sensors alone.
It therefore would be desirable to provide an electromechanical actuator control loop that eliminates undesirable phase lag that degrades system stability, with reduced control loop noise sensitivity, and reduced compensation complexity.